Challenge-response authentication is a process in which a first device authenticates a second device by sending to the second device a challenge. In response to the challenge, the second device returns a response, which is used by the first device to determine whether the second device is authentic. Challenge-response authentication can be as simple as the first device sending the second device a request for a secret password (this being the challenge), and in response the second device providing the secret password (this being the response to the challenge). If the response from the second device matches the expected response, then the second device is assumed to be authentic.
One type of challenge-response authentication works as follows. The first device sends a challenge value to the second device. The second device then uses the challenge value and secret information known to the second device in order to compute a response value. The response value is then sent to the first device. If the response value from the second device matches the expected response value, then the second device is assumed to be authentic. In such a protocol, the authenticity of the second device is linked to its knowledge of the secret information.
A counterfeit device trying to impersonate the second device would (presumably) not know the secret information and therefore would not be able to compute and provide the correct response value to the challenge from the first device.
One application in which challenge-response authentication is typically performed is in authenticating a battery used to supply power to a mobile device. The mobile device can be considered to be the first device, and the battery can be considered to be the second device. When the battery is inserted into the mobile device, the mobile device sends a challenge value to the battery. The battery must then provide a response value to the challenge. The mobile device authenticates the battery by verifying that the response value from the battery matches the expected response value.
Like reference numerals are used in different figures to denote similar elements.